[24hoursupport] Re: Cable generated interference
- From: yyixi001@xxxxxxxxxxxxxx
- To: 24hoursupport@xxxxxxxxxxxxx
- Date: Wed, 20 Aug 2003 17:52:28 -0500
Hi Robert,
I talked to Bill at the HRO in Anaheim again and relayed what you wrote,
and he says you do not want to put the ferrite beads right where the
cables all cluster together in a bundle through the hole--negative/nix
on that. You put the ferrites 'on the devices', that is, at the ends of
the cables where they terminate at your monitor, and the other end where
it terminates at the computer, right up against the plugs. Also do it to
the monitor power cords where they emerge from the monitor, and where
they plug into the wall or power strip.
The wireless mouse--if you want to eliminate it as a possible source of
RFI, switch to a cable mouse and, yes, you can put a ferrite at both
ends of the mouse cable. I asked, That would mean dragging a ferrite
around when you move the mouse, right? He said, that's correct.
Of course, like I say, I'm guessing he has detection equipment that is
so sensitive that if you pointed it at anything, he would pick up some
'rads', and then he would pick up fewer rads on his detector readouts
after putting a ferrite on both ends of the cable or cables to it, and
any reduction, even a barely detectable improvement in the RFI readouts,
is sufficient justification as far as he is concerned, for snapping on a
ferrite bead on each end of every cable attached to it. Can you imagine,
he said to put one on a mouse cable? At both ends. That's something to
think about. I would imagine that if anyone wanted to ask him to 'prove
it', and justify actually putting a ferrite bead on a mouse, he'd set up
his equipment, scan the mouse for RFI, get a reading, then pop on some
ferrites, scan it again, and inevitably get a lower RFI reading, and say
something like, "Any questions?"
Personally, I don't have that kind of a problem, so I don't see any need
for me to do anything to my equipment--yet, although I'm definitely
keeping this in mind for future reference. But if you say you have a
problem, then this is clearly the way to go, and so long as there
remains any RFI interferance, and a cable without a ferrite bead on it,
there's room for improvement.
Keep in touch!
cheers,
Roland
"Robert Carneal carnealr-at-adelphia.net |24hoursupport/1.0-Allow|"
wrote:
>
>
> Hm, that makes sense. There is a board at the back of the desk which keeps
> ladies dresses private and also holds the desk together. I drilled a hold
> dead center of it and ran the video cables right through it.
> Let me throw this at you: If I were to get some ferrite beads, and put them
> on sides of the hole (middle of cable, so to speak) that -should- reduce
> interference?
>
> The cables already have a something on each end of the cable, so I am
> guessing I just need to add some right around where they are bundled. Does
> that make sense?
>
> Also, after reading you email, I got a horror thought. I use a Microsoft
> Wireless Intellimouse Explorer. That has to have some way to
> "communicating" (I am assuming radio waves, I am not a communications
> engineer.). At the computer where the receiver plugs in, there is no
> ferrite bead at all. Should I make this a prime suspect?
>
> Thank you.
>
> Robert
>
> At 05:35 PM 8/19/2003, you wrote:
>
> >
> >Hi Robert,
> >
> >I put a post to a Ham Radio Forum, and had ten views but no answers by
> >today. So I called and talked to the HRO guy in Anaheim, California, and
> >he said it's RFI, radio frequency interferance, running down your
> >cables. He said computers are very 'dirty' for stray RFI emissions. You
> >can also get problems with interferance from flourescent lights, and
> >from radios (he didn't say if music or HAM radios) interfering with
> >computers, and vice-versa. The deal is, you need to put something called
> >a 'ferrite snap bead' on each end of each of your monitor video and
> >power cables, which 'chokes' off the RF.
> >
> >Here is a web page giving sort of an explanation of that (but don't buy
> >there; I'll get to that);
> >http://www.cardwellcondenser.com/PAGES/nr10.html
> >
> >Here is where to get the 'ferrite snap beads' (a.k.a. 'ferrite
> >clamshells', or just 'ferrites');
> >http://www.allelectronics.com/cgi-bin/category.cgi?category=235&type=store
> >
> >They're not really expensive, but the HRO guy says he has a room full of
> >HAM radio gear and computer gear, and I'm guessing he probably has the
> >accessory gear to detect his own stray rads, and likes everything
> >near-perfect, so he's telling me he puts them on both ends of every
> >cable he's got, mice, keyboard, networks, printers, scanners, and all
> >external peripheral devices. BUT--he told me you don't need to do it
> >that much. He said to just start by getting just a few of these and
> >snapping them only onto the monitor cables, so you end up with one on
> >each end of your monitor video and power cables, and see what results
> >you get before getting more of them to put on anything else. He said
> >it's 'as much art as science', and you have to experiment with them a
> >little.
> >
> >I'd guess that just doing the monitor cables may be enough, whereas
> >someone like him, he can set up his test gear and turn up the
> >sensitivity and see a very slight RFI reading on just about any piece of
> >computer gear he aims it at, and so he goes after it like that, with a
> >ferrite on both ends of every single thing he's got. But he admits it's
> >not necessary to do all that. So that's where he says to just do the
> >monitor cables first, and go from there. Or if you want to buy a whole
> >bunch of them, which is what he does, then just try to match up the hole
> >sizes of the ferrites to the cable thicknesses.
> >
> >The way you put them on, is to get the clamshell ferrite that has the
> >best match for the diameter of cable it's going around, for which an
> >inexpensive plastic caliper measuring device would help, but if you
> >don't have that just eyeball it with a ruler. You snap it on near to the
> >plug at the monitor end, then slide it over to butt it up against the
> >plug, or against where the plug comes out of the monitor, and leave it
> >there permanently. Then do the same at the other end. It should not
> >cause any other problems, and is supposed to help or cure the RFI
> >problem, which is apparently what is causing monitor interferance.
> >
> >He also said most monitors already come with a built-in 'ferrite' on the
> >video cable; it's the little cylindrical knob on the video cord that
> >makes the video cable look like a skinny little boa constrictor that
> >swallowed a D or C cell battery. That's the ferrite. I'd guess that,
> >like a rubber magnet, it's platic with iron particles or one or more
> >iron cylinders embedded in it ('ferrite' = 'iron'; I think). So I'd say
> >the idea is, if you're getting RFI, then you need to add a few more,
> >onto the other end of the monitor cable, and then the monitor power
> >cables. If that doesn't do the job, the HRO guy says to go for some of
> >the other computer externals with cables, and start playing around with
> >the ferrites. But the way it's done; you always snap them on, then slide
> >them down to either or both ends as close as possible to where it comes
> >out of the computer, or to the external device, and leave it on.
> >
> >Some of the bigger computer supply stores also sell these ferrites,
> >although the sales person at PC Mall said he never heard of them.
> >
> >Please let me know if I can help any further.
> >
> >cheers,
> >
> >Roland
> >General Class HAM Lic. KC6RRL
> >
> >"Robert Carneal carnealr-at-adelphia.net |24hoursupport/1.0-Allow|"
> >wrote:
> > >
> > >
> > > I would very much appreciate that.
> > > Thank you.
> > >
> > > Robert
> > >
> > > At 10:33 AM 8/18/2003 -0500, you wrote:
> > >
> > > >
> > > >I've been thinking I might could check with an amateur radio egroup and
> > > >ask them, and this seems like a good time to do that. I'll see what I
> > > >can come up with.
> > > >
> > > >cheers,
> > > >
> > > >Roland
> > > >
> > > >
> > > >
> > > >
> > > >"Robert Carneal carnealr-at-adelphia.net |24hoursupport/1.0-Allow|"
> > > >wrote:
> > > > >
> > > > >
> > > > > <Copy>
> > > > > The top of the page includes a sublink for 'store location',
> > listing stores
> > > > > across the US. I chose Denver, Colorado, as being sort of 'middle'
> > US, and
> > > > > the following link;
> > > > > <End>
> > > > > Thank you. I will write them tomorrow. Voice communications via
> > telephone
> > > > > isn't possible for me; I am hearing challenged and depend on lip
> > reading.
> > > > >
> > > > > Robert
> > > > >
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